This application claims the priority of Korean Patent Application No. 2001-88848 filed Dec. 31, 2001, which is incorporated herein in its entirety by reference.
1. Field of the Invention
The present invention relates to the field of image display devices, and more particularly, to an image display device and method for converting digital image data per pixel into an analog signal and driving a liquid crystal cell in response to the analog pixel signal using voltage charged by a driving circuit with a dual buffer structure.
2. Description of the Related Art
A liquid crystal display (LCD) is one type of flat display device used in computers, flat television receivers, and information appliances, and is made of a plurality of pixels having capacitive loads.
In general, an LCD consists of a plurality of pixels indicating an image signal, the pixels being driven in response to a signal that is applied via a wire. In a wire, scan signal lines or gate signal lines for transmitting scan signals, or image signal lines or data lines for transmitting image signals are connected, in the form of matrix, to a plurality of thin-film transistor (TFT) switching devices corresponding to the pixels. Each TFT is connected to a liquid crystal cell and thus displays an image signal.
As shown in FIG. 1, a conventional apparatus for driving an image display device includes a liquid crystal cell 1, a thin transistor 2, and a capacitor 3 for each pixel display unit. Gate and input terminals of the thin transistor 2 are connected to a gate signal line and a data signal line. One terminal of the liquid crystal cell 1 is connected to an output terminal of the thin transistor 2 and a pixel electrode is connected to the other terminal thereof. The liquid crystal cell 1 is connected in parallel to the capacitor 3.
The data signal line is for supplying voltage to the liquid crystal cell 1, and the gate signal line is for supplying a signal used to determine a line to which a liquid crystal cell of a scan line to be displayed belongs.
The thin transistor 2 accumulates voltage of the data signal line in the capacitor 3 to provide the voltage to the liquid crystal cell 1, in response to a signal supplied via the gate signal line.
As described above, each liquid crystal cell 1 is driven by the voltage charged in the capacitor 3.
In general, a conventional image display device displays one sheet of an image with R.G.B. cells in one vertical synchronization period ( 1/60 seconds). Therefore, in order to realize a single-panel projection television receiver using the conventional image display device, at least red, green and blue (R.G.B.) colors must be displayed within the one vertical synchronization period. However, the conventional image display device shown in FIG. 1 is not capable of driving all of the R.G.B. cells on a single panel within one vertical synchronization period.